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You probably wouldn’t have much difficulty if I asked you to imagine a bad PowerPoint presentation. Nowadays one sits through so many of them that confusing, boring or annoying slide shows are sometimes perceived as the norm rather than the exception. A research team from the universities of Stanford, Amsterdam and Harvard headed by Stephen Kosslyn explains how to do it better. In order to reap off the benefits and avoid the pitfalls of visual aids, presenters should think about avoiding weaknesses of human information processing and play on the strengths of such processing.

Kosslyn and colleagues see the task of the audience viewing a PowerPoint presentation as composed of three steps: a) information needs to be acquired, b) information needs to be processed, c) information needs to be connected to knowledge. They derive eight principles that a presenter should follow based on this analysis.

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a) encoding, i.e. acquiring information and turning it into a usable form

1) Discriminability: make it easy for the audience to discriminate colours, letters, sizes, line orientations etc.

3) Salience: use large perceptual differences to guide attention to what is IMPORTANT

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b) working memory: holding information in mind in order to integrate it online

4) Limited Capacity: understanding breaks down once too much information has to be retained

5) Informative Change: when something perceptual changes, this change has to mean something

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c) accessing long term memory: connect the new information with knowledge in order to extract meaning.

6) Appropriate Knowledge: avoid as much novel concepts, jargon or symbols as possible

7) Compatibility: the meaning of a message needs to be compatible with its form

8) Relevance: provide neither too much nor too little information

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These principles may look very obvious but they are frequently violated. From an internet sample of slide shows it became clear that on average a PowerPoint presentation violates six principles at least once. Some principles were nearly always ignored: 1) discriminability, 4) limited capacity, 5) informative change.

Now, one may argue that these principles are simply guidelines that lay people are unaware of. No wonder they get violated. However, in a subsequent laboratory experiment participants were 80% correct in choosing a non-violating slide and rejecting a bad one. Moreover, when asked to say why one slide was better, more than 80% of the correct choices were appropriately justified.

So, this study is about what one already knows but still ignores when designing a slide show. The authors use a backdrop of psychological literature to predict what sorts of principles should guide PowerPoint presentations. What they, unfortunately, fail to do is to empirically test each principle’s impact on presentation understanding and memory. As such, this study simply presents a set of guidelines, says that presentations usually violate guidelines and that most people are aware of these violations. How important the guidelines are to begin with remains unclear.

The main take-home message is that the more work a presenter does for his/her audience, the more the audience can tune into the content of the presentation. For my part I am always guided by a more memorable principle:

Look around the room and search for the newbie or the bored one or the least intelligent listener. S/he is your target audience.

For a complete list of useful rules which may help you and especially your audience, see the appendix of Kosslyn and colleagues’ paper.

6 comments

I disagree with the assertion of targeting the least intelligent listener… By “dumbing” down a presentation to the lowest common denominator you will bore the remaining members of your audience feel like you are treating them like fools.

However I like the other principles you have articulated here. They align nicely to some of the principles I have articulated on my blog.

I agree that dumbing down can go too far. Importantly, I did not find it in Kosslyn et al.’s article.

However, as I mention in the post, I personally am guided by this overarching ‘don’t overestimate your audience’ principle. Why? In academia the content of presentations is usually very advanced and the background of the audience more diverse than often realised. I am personally overwhelmed by a lot of presentations. So, in my experience, when it comes to getting a message across overestimating audience abilities appears to me the bigger problem than underestimating it.

This issue should not distract from the main take-home message of the reviewed article: take your audience’s information processing capabilities into account.

Do you think that in academia the issue is more related to the desire of the academic to demonstrate how much they know, rather than considering what is most relaevant or able to be absorbed by the audience?

From my time at uni I certainly had my fair share of proffessors who were more interested in demonstrating thee depth of their knowledge rather than what was best for the students sitting in the lecture?

The Kosslyn article, which I reviewed in the post, does not single out academia as an area where the principle of Appropriate Knowledge (which you seem to be alluding to) is particularly bad. Differences between fields (business, education, government, research…) were not found to be reliable and in any event the worst value was reached by business presentations.

So, rather than talking about academia, I think one should talk about people in general. And yes, human communication can surely be used to convey an image of oneself as intellectually superior even when this comes at the cost of conveying the primary content. I also get annoyed by this when I notice it. But just because I notice it, does not necessarily mean that the presenter notices it as well. Audience feedback can help in giving the speaker the chance to more appropriately communicate what he wants to say.

From my time at uni I remember that such feedback was usually completely absent.